1. Field of the Invention
The present invention relates to a multilayer identification card having an IC module arranged on a carrier element, the IC module being disposed in a cavity in the card and surrounded by elastic material.
2. Discussion of Background and Material Information
An identification card in which the integrated circuit in a cavity in the card is partially surrounded by an elastic embedding mass is described, for example, in German Offenlengungsschrift No. 22 20 721. In this known card, the circuit is surrounded only on three sides by an elastic mass, while the leads and connection points of the leads are rigidly fixed to the circuit in the card body. When the card is bent, the connection points between the leads and the circuit are thus especially endangered. German Offenlegungsschrift No. 22 20 721 explains, as far as the production of the identification card is concerned, that the circuit may be embedded, for example, in the polyvinyl chloride used in the production of the card. Compared to the sensitive components to be embedded, PVC is fairly hard, so that in this case one cannot really speak of "elastic embedding".
Another identification card having an integrated circuit and a method for producing it are disclosed in German Offenlegungsschrift No. 30 29 939. In the case of this identification card, for example, so-called buffer zones in the form of intermediate layers are provided in the card compound before lamination. These layers have a lower softening point than the films conventionally used in card production and are elastic in a cold state. Even before the full laminating pressure takes effect on the carrier element or the IC module, the layers with a lower softening point soften and fill in the cavities present in the area of the carrier element. In this way, a homogeneous casing is formed around the carrier element, which can then take on the full laminating pressure.
In the case of the identification card proposed in German Offenlegungsschrift No. 30 29 939, cavities present in the area of the carrier element are filled in, during, or in the initial phase of, the laminating process, with the material of softened card layers additionally present in the laminate. This means that intermediate layers in the form of additional films or coatings, which soften at appropriate low laminating temperatures but must not have any effect, if possible, on the compound of card layers themselves, must be used for the production of the identification cards.
The problem on which the invention is based is to propose an identification card having an integrated circuit and a method of producing it, which avoid the above-mentioned disadvantages. In particular, the incorporation of the carrier element should not be bound to the use of special films.
The problem is solved by the features stated in the claims.
An essential idea of the invention is to use a material for embedding the integrated circuit or the carrier element, whose properties meet both the requirements for card production and those for use of the card.
Before lamination, the cavities present in the area of the carrier element or the IC module and resulting from corresponding recesses in the card construction are filled with a material whose consistency ranges from pasty to liquid. In the following lamination process, the material, due to its low viscosity, spreads into every single existing cavity, no matter how small. This already takes place in the initial phase of the laminating process, in which the card layers are hardly heated. In the course of the process, when the card layers soften and the maximum laminating pressure takes effect, the complete encasing protects the mechanically sensitive areas of the carrier element. Since the material forming the casing is also practically incompressible, the cavity formed by the recess in the card layers retains its shape, so that the relatively hard card material cannot damage the endangered portions of the carrier element.
The cover films do not show any breaks or deformations in the area of the carrier element, either, because the material which fills in the cavity creates a pressure balance due to its consistency. In accordance with the properties of the material and the laminating temperature, the cross-linking or curing process takes place, converting the material into an elastic state either during or after the laminating process. The material which is now resilient and very ductile offers very good protection for the carrier element or the IC module in the course of the daily use of the identification card.
For the identification card according to the invention, no special additional films or layer constructions are necessary for the incorporation of a carrier element or an IC module.
According to more specific embodiments of the invention, there are cavities in the card in the area of the IC module or the carrier element, which are filled in any case by the liquid or pasty material, whereas other cavities are provided to take up any excess material. In these embodiments of the invention it is guaranteed that certain cavities which are important for the functioning of the card are filled by the material which gives protection both during production and during the use of the card. If there is an excess of material, it is forced into areas of the card which are insignificant for the same incorporation of an IC module.
Further advantages and developments of the invention can be found in the subclaims and the embodiments described in the following.